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| Paper: |
X-ray sources in Galactic old Open Star Clusters |
| Volume: |
470, 370 Years of Astronomy in Utrecht |
| Page: |
251 |
| Authors: |
van den Berg, M. |
| Abstract: |
I review the current status of studies of the X-ray sources in
Galactic old open clusters. Cataclysmic variables (CVs),
magnetically-active binaries (ABs), and sub-subgiants (SSGs) dominate
the X-ray emission of old open clusters. Surprisingly, the number of
ABs detected inside the half-mass radius with
LX ≥ 1 × 1030 erg s-1 (0.3–7 keV) does not appear
to scale with cluster mass. Comparison of the numbers of CVs, ABs, and
SSGs per unit mass in old open and globular clusters shows that each
of these classes is under-abundant in globulars. This suggests that
dense environments suppress the frequency of even some of the hardest
binaries. |
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